Curable silicone compositions are known for their excellent properties, such as resistance to heat and to cold, electrical insulation properties, weatherproof properties, repellency of water, transparency, etc. Due to these properties, the compositions find wide application in various industries. Since the compositions are superior to other organic materials with regard to their color change and deterioration of physical properties, one can expect that such compositions will find use as a material for optical parts. For example, US Patent Application Publication No. 2004/116640 A1 discloses an optical silicone resin composition for light-emitting diodes (LEDs) comprising: a silicone resin having at least two silicon-bonded alkenyl groups in a molecule, an organohydrogensilane and/or organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, and an addition reaction catalyst.
Recently, addition curable solid or semi-solid silicone materials are proposed to enable a new LED device fabrication process. For example, US Patent Application Publication No. 2008/0308828 A1 discloses an additional curable adhesive silicone resin composition comprising: an alkenyl group-containing organopolysiloxane resin; a silicon-bonded hydrogen atom-containing organohydrogenpolysiloxane resin; a platinum group metal-based catalyst; and a phosphor, and also discloses an adhesive composition sheet prepared by molding the composition. However, the composition is only limited to the use of a specific organopolysiloxane resin having linear polysiloxane segments in the structure. US Patent Application Publication No. 2011/0092647 A1 discloses a curable organopolysiloxane composition comprising: a solvent-soluble organopolysiloxane obtained by conducting a hydrosilylation reaction between an organopolysiloxane resin having at least two alkenyl groups in a molecule, and a diorganopolysiloxane having silicon-bonded hydrogen atoms at both molecular terminals; an organohydrogenpolysiloxane; and a hydrosilylation catalyst. US Patent Application Publication No. 2011/0248312 A1 discloses a silicone resin sheet obtained by semi-curing a composition for a silicone resin, comprising: an organopolysiloxane having at least two alkenylsilyl groups in a molecule; an organopolysiloxane having at least two hydrosilyl groups in a molecule; a hydrosilylation catalyst; and a curing retardant. However, their hotmelt performance was insufficient to apply to practical applications.
It is an object of the present invention to provide a reactive silicone composition capable of forming a hotmelt material. And it is another object of the present invention to provide a hotmelt material. Furthermore, it is another object of the present invention to provide a curable hotmelt composition.